Epilepsy

Question 1

Epilepsy

Answer 1

A condition characterized by recurrent unprovoked seizures caused by atypical, excessive or synchronous neuronal brain activity.

Question 2

What is critical to diagnosis of epilepsy?

Answer 2

EEG

Question 3

Pre-Ictal Pattern

Answer 3

Brain wave pattern before a seizure.

Question 4

Ictal Pattern

Answer 4

Brain wave pattern during a seizure.

Question 5

Post-Ictal Pattern

Answer 5

Brain wave pattern after a seizure.

Question 6

Interictal Pattern

Answer 6

Brain wave patterns between seizures. These can help diagnose epilepsy even if a person is not currently having a seizure.

Question 7

Unprovoked Seizures - Are they truly unprovoked?

Answer 7

Despite the definition of epilepsy seizures being unprovoked, there are triggers/causes of seizures for many people (stress, sleep deprivation, etc.) or things that make the seizures more likely.

E.g. Reflex epilepsy, thought epilepsy (a type of thought triggers a seizure)

Question 8

How effective are anticonvulsant drugs for epilepsy?

Answer 8

Anticonvulsant drugs can reduce seizures but are often ineffective (33% of individuals do not respond to anticonvulsant meds).

These don’t “cure” epilepsy.

Question 9

Untreatable epilepsy is known as

Answer 9

pharmalogically intractable epilepsy.

Question 10

Seizure

Answer 10

Happens for a variety of reasons. What happens in the brain, an imbalance of excitation and inhibition—a ‘feed-forward’ of excitation—excitation causes more exictation.

Does not always cause bodily convulsions.

Question 11

Epileptic Aura

Answer 11

Something that precedes a seizure in epilepsy (minutes to seconds prior). Can be a thought, type of smell, emotion. Auras can also be seen in migraines but it is usually more visual when in migraines.

Can also provide clues as to where the epileptic focus is (where the brain is excited during the seizure - not every seizure has a focus).

Question 12

Focal seizure

Answer 12

A seizure that does not have to involve the entire brain, usually localized to a single brain area/starts from the epileptic focus.

Focal seizures can turn into a generalized seizure - secondary generalization.

Question 13

Generalized seizure

Answer 13

Involves the entire brain.

Question 14

Secondary generalization

Answer 14

When a focal seizure evolves into a generalized seizure.

Question 15

Simple Partial Seizure

Answer 15

Symptoms are primarily sensory or motor or both. Typically no loss of consciousness. You will recognize something is unusual but still be conscious. (Can cause emotional reactions like sudden uncontrollable laughing or crying.)

Question 16

Complex Partial Seizures

Answer 16

Resistant to treatment. Disrupt and/or alter consciousness, patients engage in compulsive, repetitive, simple behaviours known as automatisms. People can also engage in more complex behaviours that appear normal. Most common in the temporal lobe (temporal lobe epilepsy).

Most common in epilepsy, ~50% of people with epilepsy experience this. Can evolve into a generalized seizure,

Question 17

Absence Seizures (Petit Mal Seizures)

Answer 17

Generalized seizure. Common in childhood, underdiagnosed. Causes a brief moment where the person looks “vacant”—often as brief as just a few seconds long. The primary symptoms are: loss of consciousness, cessation of ongoing behaviour, vacant look, fluttering eyelids. May spontaneously resolve or move to a different type of seizure.

Often the person does not even know they have had a seizure.

Question 18

Absence Seizure EEG Signal

Answer 18

Bilaterally symmetrical (cells firing in high synchrony all at once)—three per second spike

Question 19

Tonic-Clonic Seizure

Answer 19

Very severe generalized seizure. High muscle tone in the tonic phase, and shaking in the clonic phase. An intense seizure across the brain. Causes loss of consciousness, hypoxia (diaphragm not working properly) loss of equilibrium, violent tonic-clonic convulsion. Tongue-biting, urination, an cyanosis (lack of oxygen causes lips to go blue) are also common. Can cause cytotoxicity/apoptosis and brain damage if very frequent.

Question 20

Two important things to do if you witness someone having a seizure:

Answer 20

1. Time it (if 5+ mins, call 911)
2. Ease person to floor, lie them on their side, put something soft under their head

Question 21

Seizures after head injury

Immediate seizures

Answer 21

Occurring within 24h post injury

Question 22

Seizures after head injury

Early seizures

Answer 22

Less than one week post-injury

Question 23

Seizures after head injury

Late seizures

Answer 23

More than one week post-injury (can be a long time, like years).

Question 24

Seizures after head injury

Latent period

Answer 24

Time between injury and onset of late seizures. Can be years!

Question 25

Does epilepsy have one cause?

Answer 25

No, in fact, 65%/the majority of epileptic patients have an idiopathic cause. ## Footnote Some causes are vascular, congenital, or from head trauma.

Question 26

Anticonvulsant Mechanisms

Answer 26

Voltage-gated sodium channels (action potentials)... many anticonvulsants modulate the norepinephrine system, attenuate things like calcium channels and reduce neurotransmitter release. Can be glutamate receptor antagonists, GABA agonists, etc. ## Footnote So the main trend is to decrease excitation and increase inhibition.

Question 27

Anticonvulsants - Common Side Effects

Answer 27

Slowing (movements, reflexes, reaction times, cognition), negative effect on mood, can impact memory formation (glutamate), can even cause psychosis

Question 28

Vagus Nerve Stimulation for Epilepsy

Answer 28

* Started in industry rather than research * You implant a pacemaker into the person’s body * It stimulates the vagus nerve * May be to do with axons - stimulating in the middle of an axon, the signal travels back to the brain * Modest beneficial effects

Question 29

Ketogenic Diet for Epilepsy | Method and Efficacy

Answer 29

The ketogenic diet increases intake of proteins and fats, and strongly decreases carb intake. The body finds a different energy source besides carbs, converting fats into ketones with the liver. Surprisingly quite effective - for 40% of children, cut their seizures in half!

Question 30

CBD for Epilepsy

Answer 30

Psychoactive (but there are not really noticeable subjective effects). Seems to be effective (childhood epilepsy) with side effects being relatively low. Also, we do not really know what CBD is binding to.

Question 31

Brain Responsive Neurostimulation for Epilepsy

Answer 31

When pre-ictal activity is detected, an electrode surgically placed within the person's skull sends stimulation to tamp down on changes in voltage.

Question 32

Surgery For Epilepsy

Answer 32

* Involves going into the brain and removing the epileptic focus (which one identifies via aura and EEG, then they may use a subdermal grid to detect signals from wherever the epileptic focus is and figure out how large it is) * Better to take too much of the brain out than too little - you really, really do not want seizures to still occur * “No brain is better than bad brain”

Question 33

The Halle Berry Neuron Study

Answer 33

* Doctors bring in epilepsy patients for a session * Present them with a huge barrage of stimuli/imagery * Record them from electrodes on the brain (not subdermal grid) * One person’s neuron only fired above baseline rates for Halle Berry, and only Halle Berry, from all angles, even responded to the words Halle Berry * These are called “concept cells” - only respond to a certain concept

Question 34

Epileptic Focus - Most to Least Likely Locations

Answer 34

* Very likely to be in temporal lobe * Somewhat likely in frontal lobe * Unlikely in parietal lobe * Seldom ever in the occipital lobe Thus, we see there is relation between the epileptic focus and the processes of explicit learning and memory.